Commit Message

This is the failure of ACATS c34011b on SJLJ targets. We have this kludge in
Identifier_to_gnu since the Tree-SSA transition:
/* If we are in an exception handler, force this variable into memory to
ensure optimization does not remove stores that appear redundant but are
actually needed in case an exception occurs.
??? Note that we need not do this if the variable is declared within the
handler, only if it is referenced in the handler and declared in an
enclosing block, but we have no way of testing that right now.
??? We used to essentially set the TREE_ADDRESSABLE flag on the variable
here, but it can now be removed by the Tree aliasing machinery if the
address of the variable is never taken. All we can do is to make the
variable volatile, which might incur the generation of temporaries just
to access the memory in some circumstances. This can be avoided for
variables of non-constant size because they are automatically allocated
to memory. There might be no way of allocating a proper temporary for
them in any case. We only do this for SJLJ though. */
if (VEC_last (tree, gnu_except_ptr_stack)
&& TREE_CODE (gnu_result) == VAR_DECL
&& TREE_CODE (DECL_SIZE_UNIT (gnu_result)) == INTEGER_CST)
TREE_THIS_VOLATILE (gnu_result) = TREE_SIDE_EFFECTS (gnu_result) = 1;
This turns out to be problematic with recent more stringent consistency checks
because TREE_THIS_VOLATILE can be set late and thus not propagated in already
built trees referencing the DECL.
The volatile trick used here is consistent with the setjmp/longjmp semantics
but we use __builtin_setjmp/__builtin_longjmp to implement the SJLJ scheme.
Tested on i586-suse-linux in SJLJ configuration, applied on the mainline.
2011-01-04 Eric Botcazou <ebotcazou@adacore.com>
PR ada/47131
* gcc-interface/trans.c (Identifier_to_gnu): In SJLJ mode, do not make
variables that are referenced in exception handlers volatile.

Index: gcc-interface/trans.c
===================================================================
--- gcc-interface/trans.c (revision 168416)+++ gcc-interface/trans.c (working copy)@@ -6,7 +6,7 @@
* *
* C Implementation File *
* *
- * Copyright (C) 1992-2010, Free Software Foundation, Inc. *+ * Copyright (C) 1992-2011, Free Software Foundation, Inc. *
* *
* GNAT is free software; you can redistribute it and/or modify it under *
* terms of the GNU General Public License as published by the Free Soft- *
@@ -980,27 +980,6 @@ Identifier_to_gnu (Node_Id gnat_node, tr
else
gnu_result = gnat_to_gnu_entity (gnat_temp, NULL_TREE, 0);
- /* If we are in an exception handler, force this variable into memory to- ensure optimization does not remove stores that appear redundant but are- actually needed in case an exception occurs.-- ??? Note that we need not do this if the variable is declared within the- handler, only if it is referenced in the handler and declared in an- enclosing block, but we have no way of testing that right now.-- ??? We used to essentially set the TREE_ADDRESSABLE flag on the variable- here, but it can now be removed by the Tree aliasing machinery if the- address of the variable is never taken. All we can do is to make the- variable volatile, which might incur the generation of temporaries just- to access the memory in some circumstances. This can be avoided for- variables of non-constant size because they are automatically allocated- to memory. There might be no way of allocating a proper temporary for- them in any case. We only do this for SJLJ though. */- if (VEC_last (tree, gnu_except_ptr_stack)- && TREE_CODE (gnu_result) == VAR_DECL- && TREE_CODE (DECL_SIZE_UNIT (gnu_result)) == INTEGER_CST)- TREE_THIS_VOLATILE (gnu_result) = TREE_SIDE_EFFECTS (gnu_result) = 1;-
/* Some objects (such as parameters passed by reference, globals of
variable size, and renamed objects) actually represent the address
of the object. In that case, we must do the dereference. Likewise,